CN111404491A - T-shaped resistance network trans-impedance amplifying circuit with automatic voltage compensation function - Google Patents
T-shaped resistance network trans-impedance amplifying circuit with automatic voltage compensation function Download PDFInfo
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- CN111404491A CN111404491A CN202010217842.8A CN202010217842A CN111404491A CN 111404491 A CN111404491 A CN 111404491A CN 202010217842 A CN202010217842 A CN 202010217842A CN 111404491 A CN111404491 A CN 111404491A
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- 239000003990 capacitor Substances 0.000 claims description 15
- 230000010354 integration Effects 0.000 claims description 15
- 238000005259 measurement Methods 0.000 abstract description 8
- 238000009434 installation Methods 0.000 abstract description 3
- 238000012423 maintenance Methods 0.000 abstract description 3
- 230000007423 decrease Effects 0.000 description 4
- 230000003321 amplification Effects 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
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Abstract
The invention discloses a T-shaped resistance network transimpedance amplifier circuit with automatic voltage compensation, which comprises: the circuit comprises a transimpedance input circuit, a voltage follower circuit, a voltage gain circuit and a compensation voltage adjusting network circuit. Compared with the prior art, the invention adopts the T-shaped resistor network to realize the feedback resistor with super large resistance in the transimpedance amplifier, and abandons the resistor with high price, high installation and maintenance cost and large error; the voltage automatic compensation circuit is adopted to overcome the large offset voltage error introduced by the T-shaped resistor network, and simultaneously eliminate the error generated by the bias current through the large feedback resistor, so that one network solves two problems; this circuit adopts hardware to accomplish completely, compares and gathers output voltage, and rethread software carries out offset voltage and adjusts, and circuit structure is simpler, and the zero setting is faster, and the error is littleer, very big improvement weak current measurement's the degree of accuracy.
Description
Technical Field
The invention relates to the technical field of universal weak signal measurement electronics, in particular to a T-shaped resistance network transimpedance amplification circuit with automatic voltage compensation.
Background
In the field of general weak signal measurement electronic technology, for fA to pA-level current measurement, an inverting amplifier circuit is usually adopted to convert current into voltage. Since the current is very small, the feedback resistance needs to reach the order of T ohms, and such a large resistance mainly causes two problems. On one hand, the bias current of the operational amplifier forms voltage drop on the feedback resistor, and brings deviation to the output voltage. On the other hand, many resistors in the T ohm order are packaged by vacuum tubes, the price is high, the use requirement is high, the T-shaped resistance network realizes large feedback resistance by using a low-resistance resistor, and can be used for replacing a single resistor, but compared with the single large resistor, the influence of offset voltage in the T-shaped resistance network structure is large, the measuring circuit is often directly in a saturation state, and the accuracy of a measuring result is seriously influenced.
Disclosure of Invention
The invention aims to provide a T-shaped resistance network trans-resistance amplifying circuit with automatic voltage compensation, which can automatically adjust the compensation voltage of a same-phase end according to the output voltage, realize accurate zero adjustment and achieve the technical effects of weak current measurement sensitivity and dynamic range requirements.
The technical scheme of the invention is realized as follows:
a voltage auto-compensating T-type resistor network transimpedance amplification circuit, comprising:
the transimpedance input circuit comprises a low bias current operational amplifier A1 and a T-shaped resistor network, wherein the T-shaped resistor network forms a feedback resistor connected between the inverting input end and the output end of the low bias current operational amplifier, and the non-inverting input end of the low bias current operational amplifier A1 is connected with a voltage-controlled current source through a resistor R4;
the voltage follower circuit comprises an operational amplifier A2, wherein the non-inverting input end of the operational amplifier A2 is connected with the output end of a low-bias current operational amplifier A1, and the output end of the operational amplifier A2 is connected with the voltage gain circuit through a resistor R1;
the voltage gain circuit comprises an operational amplifier A3, the inverting input end of the operational amplifier A3 is connected with a resistor R1, a resistor R2 and a low-pass filter capacitor C1 are connected between the inverting input end and the output end of the operational amplifier A3 in parallel, and the output end of the operational amplifier A3 is connected with the compensation voltage adjusting network circuit through a switch K;
the compensation voltage adjusting network circuit comprises a resistor R3, an inverting integration circuit and a voltage-controlled current source, wherein the inverting integration circuit comprises an operational amplifier A4 and an integration capacitor C2, one end of the integration capacitor C2 is connected with the output end of the operational amplifier A4, the other end of the integration capacitor C2 is connected with the inverting input end of the operational amplifier A4, one end of a resistor R3 is connected with a switch K, the other end of the resistor R3 is connected with the inverting input end of the operational amplifier A4, and the output end of the operational amplifier A4 is also connected with the voltage-;
the non-inverting input terminal of the operational amplifier A3 and the non-inverting input terminal of the operational amplifier A4 are both grounded.
Compared with the prior art, the invention has the following beneficial effects:
the T-type resistance network transimpedance amplifier circuit with automatic voltage compensation adopts the T-type resistance network to realize an ultra-large resistance value feedback resistor in a transimpedance amplifier, and abandons a large resistance value resistor which is expensive, high in installation and maintenance cost and large in error; the voltage automatic compensation circuit is adopted to overcome the large offset voltage error introduced by the T-shaped resistor network, and simultaneously eliminate the error generated by the bias current through the large feedback resistor, so that one network solves two problems; this circuit adopts hardware to accomplish completely, compares and gathers output voltage, and rethread software carries out offset voltage and adjusts, and circuit structure is simpler, and the zero setting is faster, and the error is littleer, very big improvement weak current measurement's the degree of accuracy.
Drawings
Fig. 1 is a schematic diagram of a transimpedance amplifier circuit of a voltage auto-compensation T-type resistor network according to the present invention.
In the figure: the circuit comprises a transimpedance input circuit 100, a voltage follower circuit 200, a voltage gain circuit 300 and a compensation voltage regulating network circuit 400.
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.
As shown in fig. 1, the transimpedance amplifier circuit of a T-type resistor network with automatic voltage compensation of the present invention includes:
the transimpedance input circuit 100 comprises a low bias current operational amplifier A1 and a T-shaped resistor network, typical bias current value is several fA to several dozen fA, the T-shaped resistor network forms a feedback resistor connected between the inverting input end and the output end of the low bias current operational amplifier, and the non-inverting input end of the low bias current operational amplifier A1 is connected with a voltage-controlled current source through a resistor R4;
the voltage follower circuit 200 comprises an operational amplifier A2, wherein the non-inverting input end of the operational amplifier A2 is connected with the output end of a low-bias current operational amplifier A1, and the output end of the operational amplifier A2 is connected with a voltage gain circuit through a resistor R1;
the voltage gain circuit 300 comprises an operational amplifier A3, wherein the inverting input end of the operational amplifier A3 is connected with a resistor R1, a resistor R2 and a low-pass filter capacitor C1 are connected between the inverting input end and the output end of the operational amplifier A3 in parallel, and the output end of the operational amplifier A3 is connected with a compensation voltage adjusting network circuit through a switch K;
the compensation voltage adjusting network circuit 400 comprises a resistor R3, an inverting integration circuit and a voltage-controlled current source, wherein the inverting integration circuit comprises an operational amplifier A4 and an integration capacitor C2, one end of the integration capacitor C2 is connected with the output end of the operational amplifier A4, the other end of the integration capacitor C2 is connected with the inverting input end of the operational amplifier A4, one end of a resistor R3 is connected with a switch K, the other end of the resistor R3 is connected with the inverting input end of the operational amplifier A4, and the output end of the operational amplifier A4 is further connected with the voltage-controlled;
the non-inverting input terminal of the operational amplifier A3 and the non-inverting input terminal of the operational amplifier A4 are both grounded.
The present invention is further described in terms of the above circuit configuration as follows:
the low bias current operational amplifier a1 is abbreviated as a1, the operational amplifier a2 is abbreviated as a2, the operational amplifier A3 is abbreviated as A3, and the operational amplifier a4 is abbreviated as a 4.
Ra, Rb and Rc form a T-shaped resistor network, and the output voltage V1 of A1 can be represented as:
wherein, V'osIs the offset voltage of the operational amplifier A1 itself, IbBias current of A1, and input current of IAnd (4) streaming.
In the circuit zeroing mode, there is no current input at the circuit input and switch K is closed. Non-inverting input voltage V of operational amplifier A1osThere are several situations:
when in use
Vos＞IbRa-V′os
V3 is positive, the current flows to the capacitor C2 through the resistor R3, the Vc potential increases in a reverse direction, the voltage controlled current source output current increases in a reverse direction, Vos decreases, and V3 decreases.
Also, when
Vos＜IbRa-V’os
V3 is negative, the current flows out of the capacitor C2 through the resistor R3, the Vc potential decreases in the opposite direction, the voltage controlled current source output current decreases in the opposite direction, Vos increases, and V3 increases.
When in use
Vos＝IbRa-V’os
The output voltage V3 of a3 is 0, no current flows through resistor R3, the voltage on capacitor C2 is constant, and V3 remains 0.
In the zeroing mode, V3 keeps the 0 potential steady state, so zeroing can be achieved.
When the potential of V3 is 0, the voltage-controlled current source is fixedly output and is disconnected with A4, meanwhile, the switch K is grounded, zero adjustment is completed, the circuit enters a measurement mode, and the output potential V3 of A3 is in direct proportion to the input current.
By combining the circuit structure and the working principle of the invention, the ultra-large resistance value feedback resistor in the transimpedance amplifier is realized by adopting the T-shaped resistor network, and the high-resistance value resistor with high price, high installation and maintenance cost and large error is abandoned; the voltage automatic compensation circuit is adopted to overcome the large offset voltage error introduced by the T-shaped resistor network, and simultaneously eliminate the error generated by the bias current through the large feedback resistor, so that one network solves two problems; this circuit adopts hardware to accomplish completely, compares and gathers output voltage, and rethread software carries out offset voltage and adjusts, and circuit structure is simpler, and the zero setting is faster, and the error is littleer, very big improvement weak current measurement's the degree of accuracy.
Claims (1)
1. A T-type resistor network transimpedance amplifier circuit with automatic voltage compensation is characterized by comprising:
the transimpedance input circuit comprises a low bias current operational amplifier A1 and a T-shaped resistor network, wherein the T-shaped resistor network forms a feedback resistor connected between the inverting input end and the output end of the low bias current operational amplifier, and the non-inverting input end of the low bias current operational amplifier A1 is connected with a voltage-controlled current source through a resistor R4;
the voltage follower circuit comprises an operational amplifier A2, wherein the non-inverting input end of the operational amplifier A2 is connected with the output end of a low-bias current operational amplifier A1, and the output end of the operational amplifier A2 is connected with the voltage gain circuit through a resistor R1;
the voltage gain circuit comprises an operational amplifier A3, the inverting input end of the operational amplifier A3 is connected with a resistor R1, a resistor R2 and a low-pass filter capacitor C1 are connected between the inverting input end and the output end of the operational amplifier A3 in parallel, and the output end of the operational amplifier A3 is connected with the compensation voltage adjusting network circuit through a switch K;
the compensation voltage adjusting network circuit comprises a resistor R3, an inverting integration circuit and a voltage-controlled current source, wherein the inverting integration circuit comprises an operational amplifier A4 and an integration capacitor C2, one end of the integration capacitor C2 is connected with the output end of the operational amplifier A4, the other end of the integration capacitor C2 is connected with the inverting input end of the operational amplifier A4, one end of a resistor R3 is connected with a switch K, the other end of the resistor R3 is connected with the inverting input end of the operational amplifier A4, and the output end of the operational amplifier A4 is also connected with the voltage-;
the non-inverting input terminal of the operational amplifier A3 and the non-inverting input terminal of the operational amplifier A4 are both grounded.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010217842.8A CN111404491A (en) | 2020-03-25 | 2020-03-25 | T-shaped resistance network trans-impedance amplifying circuit with automatic voltage compensation function |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010217842.8A CN111404491A (en) | 2020-03-25 | 2020-03-25 | T-shaped resistance network trans-impedance amplifying circuit with automatic voltage compensation function |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113804959A (en) * | 2021-10-18 | 2021-12-17 | 常州同惠电子股份有限公司 | High-precision high-speed weak current measuring circuit and measuring method based on transimpedance amplification |
| CN115452905A (en) * | 2022-11-04 | 2022-12-09 | 唐山学院 | Electrochemical impedance meter based on smart phone and use method |
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| JPH1164394A (en) * | 1997-08-11 | 1999-03-05 | Advantest Corp | Absolute value circuit |
| CN1227013A (en) * | 1996-08-02 | 1999-08-25 | 爱特梅尔股份有限公司 | Voltage to current converter for high frequency applications |
| JP2009005014A (en) * | 2007-06-20 | 2009-01-08 | Hioki Ee Corp | Current/voltage conversion circuit |
| CN109546660A (en) * | 2018-11-22 | 2019-03-29 | 中国航空综合技术研究所 | Active power filter circuit and control method based on neural network sliding mode control strategy |
| CN211063578U (en) * | 2020-03-25 | 2020-07-21 | 杭州顾宸科技有限公司 | T-shaped resistance network trans-impedance amplifying circuit with automatic voltage compensation function |
-
2020
- 2020-03-25 CN CN202010217842.8A patent/CN111404491A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1227013A (en) * | 1996-08-02 | 1999-08-25 | 爱特梅尔股份有限公司 | Voltage to current converter for high frequency applications |
| JPH1164394A (en) * | 1997-08-11 | 1999-03-05 | Advantest Corp | Absolute value circuit |
| JP2009005014A (en) * | 2007-06-20 | 2009-01-08 | Hioki Ee Corp | Current/voltage conversion circuit |
| CN109546660A (en) * | 2018-11-22 | 2019-03-29 | 中国航空综合技术研究所 | Active power filter circuit and control method based on neural network sliding mode control strategy |
| CN211063578U (en) * | 2020-03-25 | 2020-07-21 | 杭州顾宸科技有限公司 | T-shaped resistance network trans-impedance amplifying circuit with automatic voltage compensation function |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113804959A (en) * | 2021-10-18 | 2021-12-17 | 常州同惠电子股份有限公司 | High-precision high-speed weak current measuring circuit and measuring method based on transimpedance amplification |
| CN113804959B (en) * | 2021-10-18 | 2024-05-10 | 常州同惠电子股份有限公司 | High-precision high-speed weak current measurement circuit and measurement method based on transimpedance amplification |
| CN115452905A (en) * | 2022-11-04 | 2022-12-09 | 唐山学院 | Electrochemical impedance meter based on smart phone and use method |
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